Keep the LICENSE file in lib/pythonX.Y dir
    
    Virtualenv tries to copy it.
    
    See https://github.com/pypa/virtualenv/issues/1352
    
    Virtualenv ~16.6 warns:
    
        No LICENSE.txt / LICENSE found in source
    
    Technically, it is probably possible to install the package without
    %license files, but that would simply resort to the previous noncritical
    behavior.
    
    This fix is not critical and hence it doesn't bump release, for easier
    backporting to all our Python packages.